4 days spotting, a week before expected period

I'm going to call my doctor, but wanted to check with you all first.. spotting before my period has become the new normal, but this time it showed a week early, and it's been going on for four days. It's not a lot, at all. Mostly when I wipe. Anyone had experience with this? I'm worried something more serious may be wrong. It was light pink and watery, and yesterday it turned to more of a rust color. No cramping, or any other symptoms to speak of. I've been ttc for 11 months now.